Unusual Ozonolysis of Cholesteryl and Androst-5-en-3beta-yl Acetates in the Presence of Primary Amines. Formation of A-nor-3(5--6alfa)abeo-6beta(H)-5-oxo-steroids, Confirmed by X-ray Analysis

The reaction of cholesteryl acetate with ozone in the presence of amines has been studied. Besides the expected cleavage products, B-seco-ketoaldehyde and its aldol condensation product, 5-hydroxy-6-formyl-B-nor-5_-cholestane derivative, the abnormal product, 3_-acetoxy-A-nor-3(5_6_)abeo-6_(H)-cholestan-5-one is formed as a result of a new, anomalous cleavage of the primary ozonide. The reaction conditions and isolation procedure were optimized for achieving good yield of the abeo-compound. The X-ray crystal structure analysis confirmed the formation of the unusual steroidal skeleton. It appears to be the first crystallographic analysis of the transformed steroid with A-nor-3(5_6_)abeo skeleton. No product resulting from the amine nucleophilic participation in the cleavage of ozonides was observed.